Whoa there, That depends upon so many factors it could make your head spin! Here, I'll list:
Processor: Does the new mobo support the same type of processor and socket?
Formfactor: Is it Baby ATX, mATX, ATX, etc.
RAM: What ram do you currently have? Is it the proper speed, ECC, registered or non?
Good luck on that. Tell me what kind of processor and memory you have if you know it and i'll give you the good/bad news.